JPH042495B2 - - Google Patents

Description

4, 87, 88. A document feeding device characterized by comprising:

[Detailed description of the invention]

"Field of Industrial Application" The present invention relates to a document feeding device in an electronic copying machine. ``Conventional technology'' Electronic copying machines have the following features to improve the efficiency of office work.
Some devices are equipped with a document conveying device that feeds a document set in a document tray onto a platen glass and sends the document out from the platen glass after copying is completed. Conventional document feeders include one that feeds originals set in a document tray one sheet at a time from the top layer (for example, see Japanese Patent Laid-Open No. 57-73754), and one that feeds originals one sheet at a time from the bottom layer. (For example, see Japanese Patent Application Laid-Open No. 56-56441).
There are also types that feed the document using frictional force and types that feed the document using air suction force (for example, see both of the above-mentioned publications). By the way, in a type of document conveyance device that feeds out documents from the top layer, it is not possible to add and set a new document once the document feeding from the document tray starts. On the other hand, in a type of document conveying device that feeds documents from the bottom layer, new documents can be added and set. In addition, in a type of document conveying device that uses frictional force to feed documents, for example, a feed belt and a double-feed prevention roller that is pressed against the feed belt feed the document.
Since the paper is fed out one by one, it is necessary to devise a way to prevent your finger from being drawn between the paper sheets. On the other hand, in a type of document transport device that uses air suction force to feed documents, for example, a feed belt with an air suction mechanism and an air nozzle placed opposite the feed belt to prevent double feeding are used to feed documents. Since the sheets are fed out one by one, there is no risk of a finger being drawn in between them. Therefore, when considering the addition of new documents and safety, it is preferable to use a configuration in which the air suction force is used to feed documents one by one starting from the bottom layer. ``Problems to be solved by the invention'' By the way, in conventional document feeders that use air suction to feed documents one by one starting from the bottom layer, the air blown out from the air nozzle to prevent double feeding is Since the air volume is always constant, there is a problem in that the feeding function and double feeding prevention function change depending on the number of documents placed on the document tray. In other words, if there are too many originals placed on the original tray, the adhesion between the bottom original and the second original from the bottom becomes excessive, and the amount of air blown out from the air nozzle becomes insufficient. However, these could not be separated well, resulting in double feeding. On the other hand, if the number of originals placed on the original tray is too small (one to a few), the air volume blown out from the air nozzle will be too large and lift the leading edge of the lowest original, causing the air to blow out. In some cases, the feed belt with a suction mechanism did not attract the feed, resulting in misfeed. To address this, for example, U.S. Patent No. 4,336,928
As described in the specification, it has been proposed to control the amount of air blown out from an air nozzle according to the amount of documents. however,
As described in this US patent specification, counting the number of originals in order to detect the amount of originals is undesirable because the processing is complicated and the configuration for performing the processing is also complicated. Moreover, continuously controlling the air flow rate in accordance with the exact amount of documents requires a complicated configuration of the control means, and is not necessary. Therefore, as shown in Japanese Patent Application Laid-Open No. 60-36248, it is conceivable to detect the height of the document and change the air flow rate in stages according to this height. However, the method of detecting the height of the document has lower accuracy in detecting the amount of documents than the method of counting the number of documents, so it is necessary to constantly detect the height of the document and control the air flow. When the document amount is close to the level at which the air flow rate is switched, the detected value of the document amount may fluctuate and the air flow rate may change frequently. In view of these circumstances, the present invention has a simple configuration and stable operation, and is capable of adjusting the air volume to prevent double feeding of originals according to the amount of originals placed on the original tray. It is an object of the present invention to provide a document feeding device that can efficiently feed documents regardless of the amount of documents. "Means for Solving the Problems" In the present invention, as schematically shown in FIG. Feed belt 2 with air absorption mechanism for feeding
, an air nozzle 3 for blowing air to the leading edge of the lowest layer of documents placed on the document tray 1 to prevent double feeding of documents; and an air volume blown out from the air nozzle 3. a detecting means 4 for detecting the height of the document placed on the document tray 1 and detecting the amount of the document; The air volume adjusting means is operated based on the detection result of the detecting means 4 for each predetermined number of sheets counted by the counting means, and the air volume is blown out from the air nozzle 3. The document feeding device is provided with a control means 5 for controlling the amount of air. According to the present invention, the amount of air blown out from the air nozzle 3 changes depending on the amount of documents placed on the document tray 1, so the amount of air is adjusted to be appropriate depending on the amount of documents. be able to. "Example" The present invention will be described in detail with reference to Examples below. FIG. 2 shows a main part of a document conveying device to which an embodiment of the present invention is applied, and FIG. 3 shows a part thereof. In this document conveying device, a document feeding device 12 is provided above a platen glass 11 .
The document feeding device 12 includes a document tray 13 provided at an appropriate inclination, a feed belt 15 with an air suction mechanism 14 provided below the top of the document tray 13, and a feed belt 15 provided with an air suction mechanism 14 provided below the top of the document tray 13
A double feed prevention mechanism 16 is provided diagonally above 5. The air suction mechanism 14 has air suction holes 1 on the top surface.
7, and an air suction source such as a blower (not shown) for creating a negative pressure inside the housing 18. Small holes 19 are provided at predetermined locations on the feed belt 15 corresponding to the air suction holes 17.
is provided. The lower part of the feed belt 15 is connected to an opening 2 provided at the center of the upper part of the document tray 13.
It is located at 0. The double feed prevention mechanism 16 is
Air sent from an air supply source such as a blower (not shown) is blown onto a predetermined location on the upper surface of the feed belt 15 by an air nozzle 21. The center of the lowermost leading edge of the document 22 set on the document tray 13 is attracted to the upper surface of the feed belt 15 by the air suction action of the air suction mechanism 14 . At this time, air is blown from the air nozzle 21 of the double-feed prevention mechanism 16 between the center of the leading edge of the lowest document 22 and the center of the leading edge of the second original 22 from the bottom stacked above it. As a result, only the center of the leading edge of the lowermost document 22 is attracted to the upper surface of the feed belt 15, thereby preventing double feeding. When the feed belt 15 is run in the direction of the arrow in this state, the lowermost document 2 is fed from the document tray 13.
Only 2 is sent out. This sent manuscript 2
2 is sent into the first carry-in path 23 consisting of a guide plate. At this time, the conveyance direction switching member 24 disposed in front of the first carry-in path 23 is positioned outside the first carry-in path 23 and is in a state of allowing the document 22 to pass through. The original 22 sent into the first carry-in path 23 is sent onto the platen glass 11 by rotation of the feed roller 25 in the direction of the arrow. Two pinch rollers 26 are in rolling contact with the feed roller 25, respectively. Original 22 fed onto platen glass 11
is fed to a desired copying position on the platen glass 11 by the conveyor belt 27 provided on the platen glass 11 running in the direction of the arrow, and is temporarily stopped at this position. Thereafter, at a predetermined timing, a scan unit (not shown) provided below the platen glass 11 starts driving, and copying is performed. After copying is completed, the conveyor belt 27 is run again in the direction of the arrow, and the original 22 is transferred to the platen glass 11.
Send it out from above. The sent out document 22 is guided by a guide plate 28 and is discharged onto a discharge tray (not shown) by a discharge roller 29 rotating in the direction of the arrow. When a plurality of originals 22 are set on the original tray 13, when the copying of the previous original 22 is completed, the next original 22 is sent out at this timing. When copying both sides of the original 22, once the front side of the original 22 has been copied as described above, the conveyor belt 27 is run in the direction opposite to the direction of the arrow, and the original 22 is transferred to the first side. Send it into the loading path 23. At this time, a plunger solenoid (not shown) is energized, and the conveyance direction switching member 24 is positioned within the first carry-in path 23 as shown in FIG. Further, the feed roller 25 begins to rotate in the direction opposite to the direction of the arrow. For this reason, the original 22 sent into the first carry-in path 23 is guided by the conveyance direction switching member 24 and sent into the second carry-in path 31 made of a guide plate, and is further moved by the conveyance belt 27 running in the direction of the arrow. Then, it is sent again to the intended copying position on the platen glass 11. In this state, the original 22
The back surface of the printer comes into contact with the platen glass 11, and copying is performed on the same back surface. When copying is complete,
The original 22 is ejected to the ejection tray. This document conveying device detects the height of the document 22 placed on the document tray 13 to detect the amount of the document 22, and changes the amount of air blown out from the air nozzle 21 based on this detection result. These parts will be explained below. FIGS. 4A and 4B show the main parts of the document amount detection device. A shaft 41 is mounted at a predetermined location on the frame 40 above the side of the document tray 13.
is located. A drum 42 is rotatably attached to the shaft 41. A central portion of a document amount detection arm 43 is fixed to the drum 42 . The arm 43 has a substantially Z-shape, and has a detection portion 44 formed at one end thereof and a detected portion 45 formed at the other end thereof. A wire 46 is attached to the drum 42.
A part of it is wrapped around. One end of the wire 46 is connected to a plunger 48 of a plunger solenoid 47. The other end of the wire 46 is fixed to the frame 40 via a spring 49. Transmissive optical sensors 5 are located at two predetermined locations on the frame 40 within the trajectory of the detected portion 44 of the arm 43.
0 and 51 are arranged respectively. In this document amount detection device, when the plunger solenoid 47 is excited, the arm 43 together with the drum 42 is rotated clockwise in FIG. 4A against the force of the spring 49 by the action of the wire 46. Then, the detection part 44 of the arm 43 comes into contact with the top layer of the original 22 placed on the original tray 13, and the position of the detected part 45 is brought into contact with the two optical sensors 5.
0,51. two optical sensors 5
The detection states of 0 and 51 depend on the amount of originals 22 placed on the original tray 13, and are as shown in the following table. In this table, the ○ mark represents an on state, and the cross mark represents an off state.

[Table] That is, when the amount of originals 22 placed on the original tray 13 is small, the arm 43 is rotated greatly as shown in FIG.
0 and 51 are both on. When the amount of originals 22 is a little small, the arm 453 is rotated a little more as shown in FIG. 2B, so that the first optical sensor 50 is turned off and the second optical sensor 51 is turned on. If the amount of originals 22 is a little large,
The arm 43 is rotated slightly as shown in FIG.
Both optical sensors 50 and 51 are turned off.
When the amount of documents 22 is large, the arm 43 is rotated slightly as shown in FIG. Therefore, when the arm 43 rotates, the amount of originals 22 placed on the original tray 13 is detected in four stages. FIGS. 6A and 6B show the main parts of the air volume adjusting device. A duct 62 is provided between the air nozzle 21 and a blower 61 for supplying air thereto. A valve drum 63 is arranged in the middle of the duct 62. Inside the valve drum 63, a large-diameter first drum valve 64 and a small-diameter second drum valve 65 are both rotatably arranged.
Parts of wires 68 and 69 are wound around shafts 66 and 67 of drum valves 64 and 65, respectively.
One end of each wire 68, 69 is connected to plungers 72, 73 of plunger solenoids 70, 71, respectively. The other ends of the wires 68 and 69 are fixed to the frame 40 via springs 74 and 75, respectively. In this air flow rate adjusting device, when both the plunger solenoids 70 and 71 are in a de-energized state, both the drum valves 64 and 6 as shown in FIG.
5, the air flow path is almost closed, and air leaks through these gaps. Therefore, in this state, the amount of air blown out from the air nozzle 21 is small. When only the plunger solenoid 71 is energized, only the second drum valve 65 is positioned outside the air flow path, as shown in FIG. Become. When only the plunger solenoid 70 is energized, the first drum valve 64 is positioned outside the air flow path as shown in FIG. . When both plunger solenoids 70 and 71 are excited, both drum valves 64 and 65 are activated as shown in FIG.
are both located outside the air flow path, and the amount of air blown out from the air nozzle 21 increases. Therefore, in this air volume adjusting device, the volume of air blown out from the air nozzle 21 is adjusted in four stages. FIG. 8 schematically shows the circuit configuration of this document conveying device. This device is equipped with a CPU (central processing unit) 81, and is connected to various parts through a bus line 82 such as a data bus. Among these, a ROM (read only memory) 83 is a memory in which a program for controlling the circuit is written. RAM (Random Access Memory)
84 temporarily stores various processing data.
The sensor input port 85 inputs and processes data output from the optical sensors 50, 51, etc., and connects the bus line 8 to the sensor input port 85.
This is the circuit part that sends out data onto the 2nd. Solenoid drivers 86 to 88 are plunger solenoids 47, 7
This is a circuit that controls the excitation of 2 and 73, respectively.
Also connected to the bus line 82 is a document conveyance drive section 89 for driving document conveyance parts such as the feed belt 15 . Next, the specific operation of this document conveying device will be explained with reference to a flowchart (FIG. 9). When a start button (not shown) is pressed to start the copying operation (step; Y), the CPU 81 first energizes the plunger solenoid 47 for a certain period of time, for example, about 150 msec (step). Plunger solenoid 47
When excited, the document amount detection arm 43 is rotated as described above, and the first and second optical sensors 5 are
0 and 51, the amount of originals 22 placed on the original tray 13 is detected. When both optical sensors 50 and 51 are on (step; Y), the CPU 81
It is determined that the amount of air is small, both plunger solenoids 72 and 73 are de-energized, and a mode in which the amount of air is small is executed as shown in FIG. 7A (step). Second optical sensor 50
is on (step; Y), the second optical sensor 51
When is off (step; N),
The CPU 81 determines that the amount of original documents 22 is large, and excites both plunger solenoids 72 and 73, thereby executing a mode in which the air volume is increased as shown in FIG. 7D (step). When the first optical sensor 50 is off (step; N) and the second optical sensor 51 is on (step; Y), the CPU 81 determines that the amount of document 22 is somewhat small, and the plunger solenoid 73 A mode is executed in which only the motor is energized and the air flow is slightly reduced as shown in FIG. 7B (step).
If both sensors 50 and 51 are off (step; N), the CPU 81 determines that the amount of documents 22 is a little large, and turns the plunger solenoid 7 on.
2 is excited, and a mode is executed in which the air flow is slightly increased as shown in FIG. 7C (step). Once the air volume is adjusted in this way,
The CPU 81 controls the document transport drive unit 89, and as described above, the bottom layer of the document 22 is sent out from the document tray 13 (step). When the rear end of the sent document 22 passes below the air nozzle 21 in FIG. 2, an optical sensor (not shown) detects this. Based on this detection result, the CPU 81 counts the number of originals 22 sent out from the original tray 13 (step), and then determines whether or not this number is 5 (step). This is because the amount of originals 22 gradually decreases as they are fed out from the original tray 13.
This is to detect the amount of originals 22 currently placed on the original tray 13 every several sheets, in this case every five sheets. If there are five or fewer sheets (N), the CPU 81 determines whether or not the original 22 is placed on the original tray 13 (step). This is the original tray 13
This is done by checking whether or not the document 22 is detected by a reflection type optical sensor (not shown) disposed below the document 22 using data as a detection result. If the original 22 is not placed (N), the operation of this original transport device ends. If the document 22 is placed (Y), the CPU 81 determines whether or not the next document 22 can be sent out (step). If the copying of the previous original 22 has been completed and it is possible to send out the next original 22, (Y),
The next document 22 is sent out from the document tray 13 (step), and the count value of the number of sheets sent out increases by 1 (step). When this count value reaches 5 (step; Y), the CPU 81 outputs two originals to the original tray 13.
2 is placed (step). If the original 22 is not placed (N), the operation of this original transport device ends. If it is placed (Y), the plunger solenoid 47 is energized again for a certain period of time (step),
At this point, the amount of originals 22 placed on the original tray 13 is detected, and the air volume is adjusted (step ~). In the above embodiment, the rotatable arms 43 and 2
Although the amount of document 22 is detected by a combination of two optical sensors 50 and 51, the present invention is not limited to this. For example, a plurality of reflective optical sensors may be arranged at intervals in the bulky direction of the document 22 placed on the document tray 13, and the amount of the document 22 may be detected based on the detection results of these sensors. Further, in the above embodiment, the valve drum 63 is used to adjust the air flow rate, but the invention is not limited to this. For example, the air volume may be adjusted by adjusting the output of a blower. Furthermore, it goes without saying that the air volume adjustment is not limited to four stages. "Effects of the Invention" As explained above, according to the present invention, the amount of air blown out from the air nozzle can be set to an appropriate amount depending on the amount of documents placed on the document tray. It is possible to send out the originals satisfactorily regardless of the number of originals placed on the original tray, and the reliability of sending out the originals is improved. Furthermore, the volume of the original is detected by detecting the height of the original, and the air volume is changed in stages according to the volume of the original, making it easy to detect the volume of the original and control the air volume. The configuration for this is simple. In addition, the air volume adjustment means is operated based on the detection result of the amount of originals every time a predetermined number of originals are sent out from the original tray, so that when the amount of originals is near the air volume switching level, Also, the air flow rate does not change frequently and stable operation is performed.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of the document feeding device of the present invention, and FIGS. 2 to 9 are for explaining an embodiment of the present invention, of which FIG. 3 is a longitudinal sectional front view showing the main parts of the device; FIG. 3 is a longitudinal sectional side view showing the feed belt with an air suction mechanism; FIGS. 5A to 5D are diagrams shown to explain the operation of this document amount detecting device, and FIGS. 6A and 6B are a cross-sectional plan view and a perspective view of a part of the main part of the air flow adjustment device, respectively. 7A to 7D are diagrams shown to explain the operation of this air volume adjusting device, FIG. 8 is a block diagram showing the main parts of the electric circuit, and FIG. 9 is a flowchart showing the operation of the document conveying device. It is. 11...Platen glass, 12...Document feeding device, 13...Document tray, 14...Air suction mechanism, 15...Feed belt, 16...Double feed prevention mechanism, 21...Air nozzle, 22...Document, 43...Document amount detection arm, 50, 51...
Optical sensor, 63... Valve drum, 64, 65... Drum valve, 81... CPU, 83... ROM, 84...
…RAM.

Claims (1)

[Claims] 1. Original tray 13, and original 22 placed on this original tray 13.
a feed belt 15 with an air suction mechanism 14 for sucking the bottom layer of the document and feeding the document;
an air nozzle 21 for blowing air to the tip of the lowest layer of originals 22 placed on the original tray 13 to prevent double feeding of originals; Air volume adjustment means 62 to 71 for changing the air volume in stages; and detection means 4 for detecting the height of the original placed on the original tray 13 and the amount of the original.
1 to 51, counting means 81 to 84 for counting the number of originals sent out from the original tray 13, and the detection means 41 for each predetermined number of originals counted by the counting means 81 to 84. ~
Based on the detection result of 51, the air volume adjusting means 62
Control means 81 to 8 for controlling the volume of air blown out from the air nozzle 21 by operating the air nozzles 81 to 71;